Upgrading from 0.90.0 to 0.92.0 gave me problems, so I uninstalled libbson 0.400 and mongoc 0.90.0, and made a fresh install.
Make test didn't work, there seems to be a missing file. Was it just me?

# git clone https://github.com/mongodb/mongo-c-driver.git mongo-c-diver-0.92.0
[... all fine...]
# cd mongo-c-diver-0.92.0
# git checkout 0.92.0
HEAD is now at 0163ed7... build: bump for 0.92.0!
# ./autogen.sh
[... all fine...]
# make && make install
[... all fine...]
# make test
[... tests/make_ca.pl ./tests/trust_dir ./tests/trust_dir.cnf
Generating RSA private key, 1024 bit long modulus ... ... ... ... ]
[ ... ... ]
Write out database with 1 new entries
Data Base Updated
Can't exec "c_rehash": No such file or directory at tests/make_ca.pl line 89.
failed: -1 at tests/make_ca.pl line 89.
make: *** [tests/trust_dir/done] Error 2
#